1. Field of the Invention
The present invention relates to a refrigerator with a freezer compartment, which includes a new temperature zone of freezer compartment or a compartment switchable to a new temperature zone of freezer compartment.
2. Discussion of Background
In FIG. 30 is shown a cross-sectional view of a refrigerator as shown in e.g. JP-B-427475. In this figure, reference numeral 200 designates a freezer compartment, reference numeral 100 designates a refrigerating compartment, reference numeral 700 designates an icing temperature compartment, and reference numeral 400 designates a vegetable compartment. The refrigerator is formed by an outer casing and an inner casing with heat insulating material foamed and filled therebetween. In the refrigerator, the compartments are separated and have different temperature zones. Reference numeral 2 designates a fan, and reference numeral 3 designates a cooling device. Part of air which has been cooled by the cooling device 3 is blown out into the freezer compartment 200 by the fan 2, and the remaining air is blown out into the refrigerating compartment 100, the icing temperature compartment 700 and the vegetable compartment 400.
The temperature zones in the respective compartments may be determined so that the freezer compartment 200 is set at from -18.degree. C. to -20.degree. C., the refrigerating compartment 100 is set at from 3.degree. C. to -5.degree. C., the icing temperature compartment (chilled compartment or partially freezing compartment) 700 is set at from 0.degree. C. to -3.degree. C. and the vegetable compartment 400 is set at from 3.degree. C. to 7.degree. C. for instance. The temperature zones are determined, mainly considering the storing terms and the kinds of stored food.
In particular, the icing temperature compartment can provide a longer storing term than the refrigerating compartment or the vegetable compartment to realize about one week of storage.
The freezer compartment can realize about one month of storage by freezing articles of food.
The number of families with not higher than two persons and the number of woman workers caused by a decrease number of children have recently increased, and a further decrease in housework is demanded. From this viewpoint, the icing temperature compartment and the freezer compartment have had an increased frequency of use.
However, the icing temperature compartment 700, for instance, can not always provide a proper temperature for a long term of food storage. This is because the icing temperature compartment has a temperature zone from 0.degree. C. to -3.degree. C., and because there is a good possibility that the temperature in the icing temperature compartment is in a range from -1.degree. C. to -5.degree. C. has a maximum ice forming temperature zone wherein the moisture in articles of food starts freezing and the articles are in such an unstable state to be likely to denature.
The increase number of woman workers increases opportunities to buy required articles of food on weekends. Although it is supposed to usually buy meat, fish and so on required for one week on weekends, it is often impossible to use up the bought meat and fish in one week because of a sudden change in planed meals or a change in the amount of use.
In such cases, it is usual to store articles of food in the freezer compartment in consideration of safety since the one week of storage in the icing temperature compartment is insufficient.
Although the freezer compartment can provide a quite longer term of storage than the icing temperature compartment by freezing articles of food, there is a case that a drop in the temperature of the articles of food to -18.degree. C. completely freezes the moisture in the articles of food to damage surfaces of the articles of food or make the articles of food tasteless.
In addition, it is necessary to thaw an article of food for cooking since the article is completely frozen. It is usual to spontaneously thaw an article of food or thaw an article of food by a microwave oven and so on. It usually takes more than one hour to spontaneously thaw an article of food, making the thawing extremely troublesome. Although it takes a shorter time to thaw an article of food by a microwave oven, it is often to heat the surface of the article too much when a central portion in the article starts being thawed. This is because an article of food is gradually thawed from the surface thereof toward the central portion thereof.
Unless next required part of an article of food is separated from the entire article before freezing the entire article, it is necessary to thaw the entire article at one time since the frozen article is too hard to separate the next required part from the entire article.
If a procedure wherein even unused part of an article of food is also thawed and frozen again is repeated, the article of food has freshness degraded, and it takes some time for thawing and cooking, which is contradictory to a decrease in housework.
Since the conventional refrigerator is constructed as stated above, there is a possibility that the icing temperature compartment stores articles of food in the maximum ice forming zone (from -1.degree. C. to -5.degree. C.), creating a problem in that the freshness in the articles is likely to degrade.
There is also created a problem in that the one week of storage in the icing temperature compartment has become insufficient due to a change in family make-up and an increase number of woman workers.
There is also created a problem in that the food storage in the freezer compartment damages the surfaces of articles of food since the articles are completely frozen.
There is also created a problem in that the completely frozen articles of food require to be thawed for cooking, which introduces failure in thawing and needs troublesome work.
It is also created a problem in that when an article of food is frozen, it is necessary to thaw the entire frozen article to use even a small part of the frozen article, and that the remaining unused part of the article is required to be frozen again, making the freshness in the article degraded.